Milling apparatus



March 27, 1962 J. o. CONVERSE MILLING APPARATUS Filed May 22, 1958INVENTOR.

JOHN O. CONVERSE ATTORNEY Fatentecl Mar, 27, 1962 3,027,169 MELLHWGAPPARATUS John 0. Converse, Minneapolis, Minn assignor to General Mills,inc, a corporation of Delaware Filed May 22, W53, Ser. No. 737,011 9Claims. (Cl. 241--78) This invention relates to milling apparatus andmore particularly to the construction of special stack units for compactflour milling installations.

Some attempts have been made in the prior art to arrange flour millingapparatus in a stack or frame in which the stock is fed to successivebreaking or reduction rolls and intermediate sifting devices. One suchunit is shown, for example, in Buchholz United States Patent No. 97,038,issued in 1869, in which reciprocating sifters are mounted in a stackbetween successive rollor milling units.

Stacked milling units of the Buchholz type were ap parently subject to anumber of problems, including mechanical difficulties such as excessiveheight and vibration and difficulty of control. Also, modern millingemphasis on the use of air purifiers and gyratory sifters and on complexflows for greater extraction have required an abundance of equipment,and the use of large mill buildings, which are often many stories highin order to minimize mechanical conveying by more extensive verticalconveying of the stocks. Thus such stacked mills never achievedsubstantial popularity or utility.

One improved stacked milling unit which avoids a number of mechanicaldifiiculties of the earlier units is described and claimed in thecopending application of Nandor Szasz for Milling Apparatus, Serial No.737,132, filed on the same date as the present application. The presentinvention relates to further improvements in stacked milling units andparticularly to an improved arrangement of milling units in balancedstacked mills of the Szasz type.

It is one object of the present invention to provide an improved stackedmilling unit.

It is a further object to provide a stacked milling unit in whichreciprocating sifters are arranged to minimize vibrations of the unitand in which a plurality of milling machines, such as roller mills orother breaking or reducing units, are mounted at convenient points onthe stack for easy access and control.

It is a still further advantage to provide a stacked milling unit whichcan achieve advantages of minimum handling between successive breakingor reduction steps to the maximum degree consistent with convenientaccess to the individual milling machines in the stack.

It is another object to provide an improved stack of minimum size forperformance of up to four milling operations with intermediate sifting.

Other objects and advantages will be apparent from the followingspecification, in which certain preferred embodiments of the inventionare described.

In the drawings which form a part of this application,

FIGURE 1 is a side elevation of one form of stacked milling unitaccording to the present invention; and

HG. 2 is a schematic side elevation of another embodiment of theinvention.

As shown in FIG. 1, the invention contemplates the use of a stacked millwhich includes a supporting frame indicated generally at in. Thesupporting frame includes a central supporting section 12, andoppositely extending end sections 14 and 16 which are in longitudinalalignment with each other and with the center section 12. The centersupport section may include at least two pairs of vertically extendingcolumns 13 and 20 with one column of each pair at each side of thestack.

The respective end support sections include at least a pair of verticalcolumns 22 for the end section 14 and a pair of vertical columns 24 forsection 16. An upper connecting beam 26 rigidly connects the variousvertical columns. Additional longitudinal beams or braces 28interconnect the columns 18 and 22, While further beams 3% connectcolumns 29 and 24. Suitable cross braces or beams are also used asneeded to obtain the desired rigidity, such beams extending in adirection which would be generally perpendicular to the plane of thepaper (as shown in the drawing) at suitable locations, such as 31.

According to the invention described in the copending Szasz application,a plurality of pairs of reciprocating classifying units are mounted inthe respective end frame portions. These units are arranged in pairs.Thus the pair 32 and 34- is the uppermost pair of the group. Verticallyspaced below the pair 32 and 34, the next lower classifying units 36 and38 form a second pair. Classifying units 4d and 42 form a third pairbelow the second pair, and the lowest classifying units 44 and 46constitute a still lower fourth pair. The individual classifying unitsof each pair are arranged in generally horizontal longitudinalalignment. The respective classifiers of each pair are adapted to bedriven or reciprocated in counterbalancing opposition to each other bysuitable eccentrics on drive shafts 48, 5d, 52 and 54 which may bedriven by belts from a suitable motor 56.

The individual classifying units are supported for the desiredreciprocating movement by suitable hangers 68 and 72. surfaces 76adapted to receive the stock which is fed. into the receiving end of thesifter through an inlet 8%].

Suitable reciprocation of unit 32 and other similar units is adapted toconvey the stock from this receiving end to the opposite or dischargeend of the unit and to sift the desired particles down through thescreen surface '76. As described above the respective pairs of units aredriven in counterbalancing opposition to each other by suitableeccentrics, with the eccentrics of each pair of sitters arranged exactlyout of phase with each other. Thus the sifters are at all times moved incounterbalancing opposition in their common horizontal or longitudinalplane, i.e., either toward each other or awayfrom each other.

According to a further feature of said Szasz application, a plurality ofpairs of milling units, such as breaking or reduction machines, are alsomounted symmetrically on the supporting frame. Thus a first pair of suchunits is mounted at the top of the frame in the Szasz case, a secondpair of units at the outer ends of the frame beneath the discharge endsof the first sifters 32 and 34, a third pair of units at a location inthe central portion of the frame beneath the discharge ends of the nextlower sifters as and 38, and a fourth pair of units at the outersections of the frame beneath the third pair of sifters. Thus in eachstep of the apparatus of said copending application material isdischarged downwardly by gravity from one machine to the next lowermachine.

According to the present invention, the milling machines are distributedin a novel arrangement which provides complete accessibility to all suchunits with minimum total height of the installation.

Thus all of the milling machines are located on the outer ends and topof the stack unit, with no milling machines supported within the stack,particularly within the inner central section. By this arrangement, allof the milling machines are easily accessible .and can be readilychecked by an operator for necessary adjustments, maintenance, andrepair.

As shown in FIG. 1, the upper sieve units 3-2 and 34 Each sifting unitincludes one or more screen receive stock from milling machines shown,for purposes of illustration, as roller mills 1th"; and 102. The desiredstocks are fed to roller mill 16% by an inlet 104 and to roller mill 102by an inlet 1%. The products of these respective milling machines arethen discharged at 198 and 110 respectively into the receiving ends ofthe uppermost pair of opposed sifters 32 and 34.

These sifters in turn discharge a portion of their products to secondstage milling machines illustrated as further pairs of rolls 112 and 114mounted on the outer frame portions 22 and 24. These milling machines112 and 114 then discharge directly into the receiving ends of the nextpair of classifiers 36 and 38.

According to one application of the present invention the millingmachines which receive the material discharged by the sieves of thissecond pair are located at the top of the stack rather than underneaththe pair. Thus roller mill pairs 116 and 11% are mounted at the top 26of the central frame portion, where they can be easily checked andcontrolled by an operator.

To carry the stocks discharged by sifters 36 and 38 to the respectivemilling machines 116 and 118 one or more short pneumatic sections, suchas 113 and 115, are provided. These pneumatic conveyors pick up thestock from the discharge ends of sifters 36 and 38 and carry such stockupwardly to respective cyclone separators 117 and 119. These separatorsare provided with connections 121 to a suitable pneumatic fan. The stockwhich has been lifted to these separators and which settles out of theair stream within the separators then drops to the milling units 116 and118 through suitable rotary valves 129 of known construction. Suchvalves prevent the pneumatic system from sucking air and stock up fromthe milling machines 116 and 113 and thus limit the suction to theupwardly extending pneumatic conveying tubes 113 and 115.

The material discharged by rolls 116 and 118 is then carried downwardlyby conduits 125 and 127 to the receiving ends of the third pair ofopposed sifters 4t and 42. These sifters in turn discharge theirtailings into respective milling machines 121i and 122 mounted on theouter frame portions 22 and 24. These milling machines discharge theirprocessed stocks into the receiving ends of the lowest pair of sifters44 and 46. The tailings of these sifters are then discharged at 123 forany suitable further processing.

The remaining stocks which are segregated by the various classifyingunits, and which are not to be fed to the following milling machine, aredischarged through separate outlets, as shown at 96 and 97. Such stocksmay be collected or subjected to further processing on other apparatus,according to their nature and quality.

One application of the arrangement of milling machines according to thisfirst embodiment of the invention involves the possibility of usingconventional double roller mills for the respective first and thirdmilling machines at the top of the stack. Such double roller mills areWell known and include two pairs of rolls within a single outer frameand casing, as shown at 124- and 126. Suitable dividers 128 and 1311within the respective casings maintain the desired separation of stocksfed to the different roller pairs. Thus one can take advantage of theavailability and economy of double roll stands, each of which may bedriven by its own independent power source, such as motors 132 and 134.Such units are available commer-= cially, and their repair andadjustment can be handled in known manner by operators familiar withsuch equipment in conventional milling installations.

The mounting of the milling machines at the top and ends of the stackedunit, and the location of the sifter drives at the center section of theunit contribute to ease of maintenance and adjustment and to minimumheight of the unit. Suitable platforms are provided as shown at and 17for personnel to inspect, adjust or operate the unit. Thus ladders 19are used to reach the ends of platform 15 for access to rolls 12d and122 and to sifters 4-0, 42, 44 and 46 and their drives. A ladder 2-1provides access to platform 17 from the floor level, while a furtherladder 23 extends from platform 17 to the top 26 of the unit. Suitablecross braces 31 further strengthen the unit as needed. Thus all portionsof the stacked mill are readily accessible to an operator.

It is possible, according to this invention, to vary the exactarrangement of sifters and milling machines to provide increasedprocessing flexibility. For example, if a longer classifying step wereneeded for material discharged from rolls 112 and 114, the tailings orother material discharged from sifters 36 and 38 could be fed directlyto the next lower sifters 4t and 42. In such a case, the upper rolls 116and 118 may receive stocks from one or more prior external sources,rather than from sifters within the same stack. Or the pneumatic liftingconveyors 113 and could be connected at some other point in the stackedunit, e.g., at two of the outlets 96 and 97, or at outlets 123 toprovide a difierent cycling or recycling flow.

One such preferred modification of this invention is shown schematicallyin FIG. 2. Here the frame 151 supports upper and lower pairs ofreciprocating classifiers 153, 155, 157 and 159. The upper sifters 153and 155 are driven from a common central drive shaft 161 incounterbalancing opposition. The lower sifters 157 and 159' aresimilarly driven from a common drive shaft 163. Sifter 155 receivesmaterial discharged by a first milling machine which is shown as havinga first pair of rolls 166. Stock is fed to roller mill 16-5 at 167 fromany desired source.

One fraction of material from sifter 155 is then discharged into aroller mill 169 at the end of the frame. Roller mill 169 then feedsstock directly to sifter 159. One fraction, such as the tailings fromsifter 159, is then fed by a pneumatic conveyor shown schematically at171 to a cyclone separator 173 and thence to a second pair of rolls 175at the top of the frame. The two pairs of rolls 166 and 175 arepreferably combined in a single housing as a conventional double rollstand.

From rolls 175 the stock is discharged to sifter 153 of the upper pair.One of the fractions discharged from sifter 153 then drops to rollermill 177 at the opposite end of the frame from roller mill 169. Fromroller mill 177 the stock is discharged by gravity to sifter 157 of thelower pair, and the classified fractions are then discharged from thesifter at 179 for collection or appropriate further processing.

The device of FIG. 2 is particularly useful as a stacked mill unit forperformance of successive first, second, third and fourth breakingoperations on cleaned and tempered wheat, with intermediate scalping orclassifying to separate such middlings stocks and flour as may beproduced at each breaking step before the remaining stock is fed to thenext break.

In all of the embodiments described, the stacked unit advantageouslyincludes a plurality of opposed sifters mounted in pairs in a frame, anda plurality of milling machines mounted on the top and opposite ends ofthe frame. The advantages of short direct gravity discharge from upperto lower units and the balancing out of horizontal vibrations which tendto shake and bend the frame can be maintained throughout the majorportions of the unit. Yet extreme flexibility in processing sequence andthe advantages of ready access to all milling machines can also beachieved by suitable arrangement of the discharge connections and by theuse of relatively short pneumatic lifts at not more than one or twopoints in the unit. In the embodiments shown, the use of one or moreconventional double roll stands for the desired pairs of millingmachines at the top of the frame offers further advantages of economy,compactness and convenient adjustment by operators already familar withsuch units.

According to the foregoing description compact arrangements for stackedmill units have been provided with reciprocating sifters arranged inbalanced opposed pairs and with associated milling machines, such asroller mills, located in balanced arrangements at the top and ends ofthe stack for convenient access and control. In this specification theprinciples of the present invention have been set forth, together withsome of the ways of practicing the invention.

I claim:

1. A stacked fiour milling unit for a grain milling installationcomprising a supporting frame having a central support section and firstand second oppositely extending end support sections aligned along acommon longitudinal axis with said central support section, at least twovertically spaced pairs of opposed longitudinally reciprocatingclassifiers mounted in said frame, with the respective first and secondclassifiers of each pair extending from said central section to saidfirst and second opposite end sections, means for reciprocating eachclassifier in horizontally counterbalancing opposition to its oppositealigned classifier, first and second pairs of milling rolls mounted atthe top of said central frame portion above the upper pair ofclassifiers, means for discharging material by gravity from said firstand second pairs of rolls directly to the inner ends of the respectivefirst and second upper classifiers, third and fourth pairs of millingrolls mounted respectively at the first and second end support sectionsof the frame in position to receive material by direct gravity dischargefrom the outer ends of the respective upper classifiers, said third andfourth pairs being located above the lower pair of classifiers inposition to discharge stock directly by gravity into the outer ends ofthe respective first and second lower classifiers, and conveying meanslocated to receive material discharged from the inner end of the firstlower classifier and connected to lift said material upwardly anddischarge it to said second pair of rolls at the top of the centralframe section.

2. Astacked flour milling unit according to claim 1 in which said firstand second pairs of rolls at the top of said central support section arecombined in the common housing of a double roller mill stand having aseparate inlet and outlet for each pair of rolls and a single commonpower source driving both pairs of rolls.

3. A stacked flour milling unit for a grain milling installationcomprising a supporting frame, at least three vertically spaced pairs ofhorizontally extending, longitudinally reciprocating classifiers in saidframe, means supporting said classifiers in opposed pairs, driving meansfor reciprocating the classifiers of each pair in counterbalancingopposition to each other, and at least four pairs of milling machinesmounted on said frame, with two pairs of said machines mounted with onemachine of each pair at each end of the frame, and with two pairs ofsaid machines at the top of said frame, means for discharging stock bygravity directly from the milling machines of one of the two pairs atthe top of the frame to the inner ends of the classifiers of theuppermost pair, from the outer ends of the classifiers of said uppermostpair to the milling machines of one pair at the ends of the frame, fromsaid one pair of end machines to the outer ends of a second pair ofclassifiers, from the remaining pair of machines at the top of the frameto the inner ends of a third pair of said classifiers, and from theouter ends of the third pair of classifiers to the milling machines ofthe remaining pair at the ends of the frame, and means for conveyingupwardly and into said remaining pair of milling machines at the top ofthe stack the stocks discharged by the inner ends of said second pair ofclassifiers.

4. A fiour milling unit according to claim 3 in which said means forconveying stocks upwardly includes two separate pneumatic conveyinglegs, one conveying stock discharged by one classifier of said secondpair to one milling machine of said remaining pair at the top of thestack, and the other leg conveying stocks discharged by the otherclassifier of said second pair to the other milling machine of saidremaining pair at the top of the stack.

5. A stacked flour milling unit for a grain milling installationcomprising a supporting frame having a central portion and twooppositely extending end sections aligned along a common longitudinalaxis, a plurality of vertically spaced, horizontally-extendingclassifiers in. each section, means supporting each classifier of eachsuch section for longitudinally reciprocating movement along said axisand in substantial alignment with a corresponding classifier in theopposite end section, means for reciprocating each classifier incounterbalancing opposition to its opposite aligned classifier, aplurality of milling machines supported on said frame in balanced pairs,all of said milling machines being mounted at the top and ends of saidframe, with the two machines of a first pair mounted at the top of saidcentral portion immediately above the upper pair of classifiers fordischarging material from said first two machines directly to thereceiving ends of said upper classifiers, a second pair of third andfourth milling machines mounted at the outer portions of said respectiveend sections immediately below the uppermost classifiers in position toreceive material by direct gravity discharge from such classifiers, saidsecond pair of milling machines being located immediately above a secondpair of said opposed classifiers in position to discharge stock bygravity directly into said second pair of classifiers, a third pair offifth and sixth milling machines mounted at the top of said centralportion, and means for lifting materials discharged by said second pairof classifiers and conveying said materials into the respective fifthand. sixth milling machines at the top of the stack, and a third pair ofsaid classifiers mounted in said frame below said fifth and sixthmachines and adapted to receive stock by gravity discharge from saidfifth and sixth milling machines.

6. A stack unit according to claim 5 in which said first and third pairsof milling machines consist of two separate standard double roller flourmill machines, each having two sets of rolls with separate inlets andoutlets for each set of rolls, and with one set of rolls in each doubleunit serving as the first pair of milling machines, and with the otherset of rolls in each unit serving as the third pair.

7. A stacked flour milling unit according to claim 5 having a fourthpair of seventh and eighth milling machines mounted at the outerportions of said respective end sections immediately below the thirdpair of classifiers to receive material by direct gravity discharge fromthe outer ends of said third pair of classifiers, and a fourth pair ofopposed classifiers mounted with their outer ends located immediatelybelow to receive stock by direct gravity discharge from the fourth pairof milling machines.

8. A stacked flour milling unit for a grain milling installation, saidunit comprising a supporting frame having a central support section andtwo aligned oppositely extending end support sections, a plurality ofvertically spaced pairs of longitudinally reciprocating classifiersmounted in said frame, with the inner ends of each classifier at saidcentral section and their outer ends at said end sections, the dischargeend of at least one lower classifier being located at the centralsupport section, driving means for reciprocating the classifiers of eachpair in counterbalancing opposition to each other and thereby conveyingstock along said classifiers while at least partially classifying thestock, a plurality of pairs of milling machines all mounted at the topand end portions of said frame in positions to discharge materialdownward- 1y by gravity to appropriate classifiers in said frame, andmeans for conveying stock upwardly from the discharge end of at leastsaid one lower classifier at the central support section to one of saidmilling machines at the top of said unit.

9. A stacked flour milling unit for a grain milling installation, saidunit comprising a supporting frame having a central support portion andtwo aligned oppositely extending end support portions, a plurality ofvertically spaced, horizontally extending longitudinally reciprocatingclassifiers supported on said frame and arranged in opposed pairs forreciprocating movement of each classifier along a common longitudinalaxis in said frame in alignment with the corresponding oppositeclassifier of the same pair, means for reciprocating each classifier inhorizontally counter-balancing opposition to its opposite 10 alignedclassifier, a plurality 01' pairs of milling machines mounted on saidframe and connected to appropriate classifiers in a desired processingsequence, all of said pairs of milling machines being mounted at the topand ends of said frame in positions to discharge material downwardly bygravity to appropriate classifiers in said frame, with two pairs of saidmilling machines mounted at the top of said frame, the classifiers of atleast one pair having their discharge ends located in the central frameportion, and conveying means for receiving stock discharged by said onepair of classifiers at the central frame portion and feeding said stockupwardly to one pair of said milling machines at the top of said frame.

References Cited in the file of this patent UNITED STATES PATENTS 97,038Buchholz -Nov. 23, 1869, 267,347 Hollingsworth Nov. 14, 1882 806,865Benesh Dec. 12, 1905 1,377,976 Smith May 10, 1921 2,081,283 Ryan et alMay 25, 1937 FOREIGN PATENTS 247,649 Great Britain Feb. 18, 1926 845,741Germany Aug. 4, 1952

